Telephone system



June 24, 1930. R. F. STEHLIK 1,767,362

TBLEPrioNE SYSTEM Original Filed July s, 1926 4 Sheets-Sheet 1 1m; Rudnlh P? Ema-1k I R. F. STEHLIK TELEPHONE SYSTEM June 24, 1930' 4Sheets-Sheet 2 Original Filed July 6, 1926 Invlnlur' fiud l ah F STEhlik7 m Hit- June 24, 1930. R. F. STEHLIK I TELEPHONE sys'rsu Original FiledJuly 6. 1926 4 Shoots-Sheet 3 June :24, 1930. R; F. STEHLIK 7,8

I TELEPHONE SYSTEI Original Filed July 6, 1925 4 Shoots-Sheet 4 PatentedJune 24, 1930 I UNITED STATES PATENT OFFICE RUDOLPH F. STEHLIK, OFCHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA-WARE TELEPHONE SYSTEM Original application filed July 6, 1926, SerialNo. 120,547. Divided and this application filed October 27,

1927. Serial This invention relates in general to telephone systems butis concerned particularly with such systems in which line finders areemployed to connect an idle trunk line with a calling line; and theprincipal object of the invention briefly stated, is the production of anew and improved finder switch system,

which is so designed as to permit cheapness in manufacture andmaintenance without impairing the reliability and ciiiciency of thesystem.

Finder switch systems which have been devised heretofore employ one ormore relays individual to each line in the system, those relays beingoperated, when that line makes a call, to start a finder in operation tocon nect with that line. In addition to the relays individual to thelines such systems have employed a certain amount of control equipmentcommon to a group of lines, through which equipment the actual settingof the various finders of the system is exercised. The combination ofindividual line relays and common control equipment for a group oflines, makes the initial cost of the system and the expense ofmaintenance, so high to be objectionable. A relay is not an expensivedevice, however and individual relay for every line in an exchange runsinto considerable money, as obviously there would be ten thousand ofsuch relays in a ten thousand line exchange.

In accordance with one of the objects of my invention I provide a tinderswitch system which uses no individual relays to connect the lines withthe control equipment but rather uses a single line and cutofi' relayset common to a relatively large group of lines.

As the principal and further object of the application I provide a newand improved line equipment of the constantly moving type, to searchover the group of lines to which it is common, and to associate callingones of said lines with the line relay which is common thereto thatrelay energizing to control a finder and equipment, to operate thatfinder into connection with that'linc.

As a further object of my invention I arrange the constantly moving lineequipment so that it acts as an impulse sender, delivering impulses tothe motor magnets of a finder switch to step that switch into connectionwith the calling line.

As a further object of my invention I use finder switches similar instructure to the well known rotary line switch whose wipers have nonormal position remaining when not in use on the contacts last used,modified and improved by the inclusion of a marking wiper and associatedcontrol 7 apparatus, through which the position in which the finder isstanding is marked in the control equipment, to determine the number ofimpulses which must be delivered to the finder magnet to position itswipers upon the contacts of the calling line.

In the instant application, the claims are directed to the constantlymoving switch mechanism. The features of the other objects are beingclaimed in my co-pending application Ser. No. 120,547, filed July 6,1926, of which this application is a division.

Automatic telephone systems of the well known type employ a connectorswitch which depends upon the finding of a battery potential on the testcontact of a called line for the establishment of a connection to thatline. That battery potential is supplied to the testing contact throughone of the individual relays associated with that line. Since in thefinder system of the present invention there are no individual relaysassociated with the line, it is necessary to provide a connectorarranged to establish a connection with one of these lines.

Further objects of my invention not specifically mentioned here will beapparentfrom the detailed specification and claims which follow.

The drawings comprising Figs. 1 to 7, inclusive show sufficientmechanical and electrical details to enable a clear understanding of myinvention. Figs. 1 and 2, when arranged with Fig. 2 beneath Fig. 1 withcorrespondingly numbered lines in alignment, show the usual circuitdetails of an embodiment of my invention. Figs. 3 and 4 are respectivelyside and front views of the constantly rotating line equipment switchused i .z i

H r in l lgh. o

more Fctail. I t

ill tinder l 'onneclcd tor l). and having ac. subscrihens lines. Theselector E i the w ll lcnown vipers are lnoved ii a vertical directionunder the control of the calling device at the subscribe station. an:the: r -d automatically u...cr t. 1 control a local testing circuitv topicl; out the ti "e trunk in the i ltrowg'er tvpe ot twoonotion switch.whose selected griun. in this c *se liil leading to the connector (j:eourse it will he inider=tood tln oral and third eel lines that can hebe increased. but essential part oi the inclusion ol se(: the to numberol showi. and the selector i1 ehown only in outlined form. Theeonncct'n' I1. may he of the well known Stronger t vp t-wo-niotuin typeswitch. whos wipers are a vertical direction to $0.1m. hanks. and thenin a hori; to select the desired line in connector di "in o from the -1both the vertical and rotary motions of the shaft are under the controlof the 'a l n device at the subacribcrs station. canineotor H ditlersfrom the well knov-cn rltrowt'er conne tor in that the private ortesting wiper does not have to lind battery in order to Switch throughand connect with the called line. In the well known Strowg'cr autoinatictelephone e: c1 an idle line designated by a high lt" stance batterypotoi tial found on the contacts enoounipred by the testing wiper. and abusy line is de natcd lrv a ground po contacts. ln the anvil system itis necess the conector an'xountcrs order to switch hroug' an the walledline. n lilOillif-Yll connector in accordmwe wthis invention, l haveretained the busy guarding feature. that is; a circuit is proviocd suchthat the coni'iector will not switch through and connec w't l a call-2dl ne it the test wiper oi the con :tor eneonrters ground potential onthe test contact of tint line. however. I have noditied the ciroui ofthe connector :so that it un'nccesaarv for t in .l direction level, theor in that the same ed in thin wiper o'l potential in connect w n heidai'd the objects of the gears 31 and I-lll. .l also show i iber tationB which is identical in every respect with the subscribers station A inFig. 1. It will he noted that the lines leading from the subscribersstations A, and i3 terminate only in the l'JtlllliR ot the finder l5 andot the line equipment LE, being dcvoid of the usual individual line andcutoli' relay through which the tinder switches u--zed licretolbre havelfiLQi: controlled. Amociated with and individual to tlri line equipmentLE is the relay equipment R, through i i the finders arc control ed topink-up ..in;; line in the manner which will he explained in detailhcrciiniltcr. In Fig. 2 I also show the finder al otter FA, which ismechanically similar to the well known rotar e switch. whose wipers movein a tor vnrd direction only. and stand when idle upon the contacts lastuanl.

I l 3 and -l I show the inecluini 'al or the line equipment LE of Fig..2. that equipment being oincxxhat similar to the vmil known Strowg'jcrrotary line switch. in that the wipers move in one dire tion only. Theline equipment in thi raw nu chanically larger than the Linc ;--:witchand turihi-r arranged so ll'lsli the wipcrh ariconstantly moving over nohaul: (,'o.'lt(lCl-T.

which consists of? tllc hank ;l il)l!1l1l\' 2-311. which eoinpri: liverov-v of contacts placed in SJllli-(fllt'lt. there being: contacts inhzrlt. h viper iuxtlll llics are carried on the rivc shaft Illa which is(ll'iYz-ll Eli! ar ya: 3 and i313. and which is sup by thrn 1.--,upportin 'l'ranic coiinn'is'ng 2-;Ul. 2):?2 :i. lll). Contact with lthe rota:

f wipers is obtained by means. of and brush. the brushes being do as307. s and 30$). I (Enrin shown dcaignatcd us 2. be noted that th: slipring for a such as the rin; 12 for the wiper placed at the side so thattill that wiper wet li iictwccn it and the Drill set. That i:-'. thebrush engaging ring 312 will lie belwcen wiper :ets 11'' and iginited nvi the i;

115. In the well known rotary line switch after which this lineequipment is patterned, the brush through which connection made to awiper set, lies between the memhe of that set. Since the mechanism LE isconstantly moving, the line switch brush arrangement will result inexcess ve wear, and I have therefore provided the arrangement mentonedaboy'e to reduce this wear much as possible.

Figs. and 6 show respectively the front and side view of the finderswitch such as F of Fig. 1 which I propose to use in an embodiment ofthe invention. It will be noted that this finder is quite similar to theaforementioned rotary line switch, and that I have added another wiper32, and a control magnet 10, which controls the movement of the wiper 32through the. retaining pawl. 502. This wiper 152 is mounted upon thesame shaft as the main wipers, to 3;}, inelusive, and is arrangcd torotate with them, or to rotate imlependently. Attached to the main wiper.Jembly, is the m. p 506, and attached to the wiper 32 is the stop 509.Lying over on the main shaft 510 is the retaining spring 507, whichwound up when the wipers 30, 31 and 83 are advanced, and the wiper 32 isheld stationary by the retaining pawl 502. Subsequent ci'iergizatiou otthe magnet 10, with draws the pawl -52 from the ratchet wheel 508 of thewiper assembly 32, permitting the springs 507 to unwind and advance thewiper until the step 509 (engages the stop 506 of the main wiperassembly, at which time wiper 2 32 will come to rest in line with theremaining wii'iers of the switch. The wipers of the switch have accessto a semicircular bank, containing 25 contacts in each row, and in this0 there are four rows of these contacts. 1110 number of contacts in eachrow, and the number of rows of contacts of the finder F can be increasedor decreased, it being necessary only to keep the number of contacts inthe row the same as the number of contacts in the rows of the banks ofthe line equipment LE shown in Fig. 3. In Fig. 5, and Fig. 6, the Wiper32 is shown in different positions with respect to the main wipers 30,31, 33, the positions being altered to enable a clearer understanding ofthe structure.

Fig. 7 shows a schematic representation of the bank contacts of the lineequipment LE, showing the order in which the wipers 115 to 119 encountertheir respective contacts. It will be noted that with the wipers movingin the direction shown by the arrow in F in. 2, wiper 117 firstencounters the contact S belonging to a particular line. li ipers 115and 119 engage the contacts 2 and 1 respectively, at the same time,wiper 11G engagi contact 1 a brief interval later. and wiper 118 engagescont a-ct \V after wipers 115, 117 and 119 have swung free from their respective contacts. Contacts S, 2' 1', i, and \V comprise a group ofcontacts which is individual to one line, there being 25 such groups inthe line equipment as shown in Figs. 3 and 4.

In order to sii iplif y the drawings as much as possible I have shown a.plurality of batteries, whereas in an actual installation these would bebut one battery, preferably with its positive pole grounded.

The operation of the system of my invention is briefly as follows: Theconstantl moving line equipment LE together Witi the relay group R,takes the place of the usual individual line and. cut-off relays of thewell known finder switch systems, and operate jointly to control thepositioning of the wipers of the finders such as F, upon the contactsleading to a calling line such as A. When a line initiates a call, forexample, the receiver is removed from the heck of substation A, thatline is in a position to pick up a fii tor and start a call. The removalof the receiver from substation A does not accomplish any function untilthe wipers of the line equipment LE engage the bank contacts associatedwith that line. When the contacts 115 and 119 of the line lpment engagethe contacts 1' and 2 which are associated with the calling line A, a.circuit is completed over the loop of the calling line for thestartrelay in the relay equipment R. That relay energizing to prepare 0'*cuits for the subsequent control ot the finder F. Since the finder Fhas no normal position, it may happen that its wipers are standing uponthe contacts associated with the line A, in which case it will not benecessary to deliver any impulses to the finder F, but only necessary toswitch that finder through and connect the calling line with the firstselector E. After the wipers 115 and 119 have found a closed loop andenergized the start relay, the marking wiper 116 has to determine theposition of the finder F, and if that finder is standing upon thecontacts of the line A, a circuit is completed through the marking wiper116, and the control equipment R switches the finder through withoutdelivering impulses to it. In. a majority of instances it will benecessary that the finder he stepped one or more steps to setnts wipersupon the contacts of the calling line, in which case no circuit will becompleted through the marking wiper 116. As the line equipment LEcontinues to move, pulse wiper 11S encounters the contact V, closing acircuit through the control equipment R and the finder allotter FA tothe motor magi of the finder F, energizing it preparato v to advancingthe finder wipers one step The energization of the motor magnet of thefinder F advances all of the wipers except the marking wiper 32, whichis under the control of the individual magnet 10. When the controlequipment R is taken into use. all oi the wipers except wipers 118 and116 or LE are temporarily cut out of service, since they have no furtherfunction in. connection with the setting of the present call. V1191; theequipment rotates so that the wiper 116 er gages the next contact in itsrow. it tests that contact to determine wl ether or not the wipers ofthe tinder have been moved a sutlieient numher of st ps to position'themupon the eonacts lling line, and it the wipers are so p ed a circ titcompleted through wiper 116 to switch through the finder and open thepulsing circuit so thatno further impulses will he delivered to it. Inthis --er the finder is advanced under the con rol o-t wipers 11S and116 of the line equipment LE. hen the calling line i: found, and thefinder smtehes through, th line eouipment and the relay group R arereleas fthe tinder allotter FA stepped ahead, to automatically preseleetthe next idle finder of the group, and ociate it with the equipment R inreadiness for the next call.

To explain a little more tully the ope ation of the marking wipers inconjunction with the control equipment R and the line cuuiru'nent LE. itwill lie noted that wiper 110 of the tinder allotter FA places ground poential upon the conductor i l) and the wiper 3-2 of th tinder 1. ll iththe wipers of F and FA in the position shown in Figs. 1 and and a callis 11. ited on the line terminating in the cor tarts o t wh ich thewipers 115 and 119 are resting, hat line will also appear in thecontacts upon which wipers 30 and 3 of the finder l are rest uo, acircuit may then be traced from ground on conductor 80 through wipercontact on, conductor a, contact g, wiper 116, through springs 128 whichare now closed. through the cu-otl' relay 106 4-1 the control equipmentthat relay energizing:

to prepare a switch-through circuit to sp nos 1% and to open theimpulsing circuit at springs 132. 11 a call is init ated by line onespace ahead or where the w pers of the tinder F are no,

inc. wiper 116 which is then er in with the contact .71. will not llllla ground potential and the switclbthrough circuitrill not be completed.LC(',l'(llilfl:ly an impulse will be sent to the finder F, to more thewipers 30, 31 and 33 one step in the direction indicated by the arrow.Similarly the wipers 115 and 119 of the line equipment LE are moved onestep, at wlnch time wiper 116 again engages contact ,1. and the circuitfor 'ela 106 is completed as be fore and the finder F is switchedthrough after llZtYlllQ taken one. step. Magnet 10 of the finder F isthen energized, and the wiper 32 released and moved under the control ofspring DOT into alignment with the remaining wipers of the switch. Itthe 11115 A is the cei ing hue. with the wipers oi toe rant u: l; in theposition shown in lug. 1. it will be net, i r to more the wip rs two stego the contacts of that. line. The ciituit th sirirt relay will becomplet d when lh u :15 engages the contact 2, the wiper 1 engages thecontact 1.

and. the, wipe. 111 engages the contact 1'. "clay 1W will not he closed,

the finder more in opposite directions, that is the wipers oi" thetinder F move.

from line 1 to line 2:),

while the wipers of lin event LE more from line 27) 1 rue wipers of thefinder F were on line 1. and line called, it be new .y to more thewipers of the finder l 21 steps in order to engage the c ntacts ot thecalling line. Similarly it the ipers oi the tinder are standing: on thecontacts in [he 10. and line 15 calls itwill he nc essar to more the'ipers steps in on. n to hri a them in engagement with the onta ts ofthe calling line.

Having thus described my invention in general. I will now proceed with adetailed description of its operation.

to i 1e 1 hen the receiver is removed from the hook switch oi thestation A, a bridge is completed across the line conductors ,1 and :3.that bridge in 'ludinp: the t *ansniitter. receirer. and mpulse fut-.pgsin series. The closure of the dire t current bridge across the lineconductors is without ell'ect until the crs of the constantl moving lineequipment LE engages the contacts of that line, in this case thecontacts 1' and 2 at which time a circuit for the start relay 103 of theetpiiprnent P. is closed. that circuit being tracethte trrnn ,Qrorudthrough springs conductor 131), wiper 119 now engaging contact 1.conductor 1. through the suhscribens loop and the SlllJrliltlOll toconductor 2, contact i3. wiper 115. conductor 116. through springs 12:).through the upper winding o'l relay to grounde battery. Relay 10 1: andits br ak contact, springs 122.

thence over two paths in parallel, the one through the upper winding ofrelay 105 to grounded battery, and the other through the lower windingof relay 103, through the lower winding of relay 102, to groundedbattery, energizing relays 102 and 105. Relay 103 is thus maintainedenergized independent of its initial circuit which is broken by theenergization of relay 102 to operate springs 120 and 121. Relay105energizes and at spring 127 and its make contact closes a circuitthrough conductor 1 15, through the winding of the motor magnet 101 ofthe finder allotter FA, energizing that magnet preparatory to advancingthe wipers of the allotter one step. Relay 105 at springs 128 closes apoint in the circuit of relay 106, that circuit being held openelsewhere at the moment. Relay 105 at springs 126 closes a highresistance ground through conductor 140 to the finder F, that circuitbeing traceable from ground through resistance 129, spring 126 and itsmake contact, conductor 140, wiper 111 of allotter FA, conductor 81,through the winding of relay 11, through resistance to grounded battery.Relay 11 when energized in series with resistances 129 and 35 is capableof closing springs 34, but not sufliciently strong to operate theremaining springs in its assembly. The closure of springs 34, prepares atesting circuit which will be explained in detail hereinafter. Relay 103upon energizing, closes at spring 123 a point in the impulsing circuit,preparatory to stepping the wipers of the finder if necessary. Theoperation of the system from this point on depends upon whether or notthe wipers of the finder F happen to be standing upon the contacts ofthe calling line A at the time.

Fin/(707 standing on calling Zinc Assume first that the wipers of thefinder F are standing on the contacts of the calling line, that is wiper30 engaging contact 2",

' and wi )cr 33 en a in contact 1" and wi er 32 is engaging the contact0. In this case it will not be necessary to send any impulses to thefinder, and. the circuit will. be closed through wiper 1.10 of thefinder allotter FA, conductor 80, wiper 32 of the finder F now engagingcontact 0, conductor 0, contact 2', wiper 116 which is engaging thatcontact, conductor 1 17, through springs 128, through the winding ofrelay 106 to negative battery. Relay 106 energizes and at springs 132opens a point in the impulsing circuit, to prevent the delivery of anyimpulses to the motor magnet of the finder. Relay 106 at springs 131closes parallel circuits for the lower winding of relay 105 to groundedbattery, to maintain that relay in its energised position independent ofthe previously traced circuit through springs 125, and through the lowerwinding of relay 104 to grounded battery to energize that relay. Relay104 upon energizing at spring 125 opens the circuit previously tracedfor relays 102, 103, and 105, and at springs 121 and closes a substitutecircuit through the upper winding of relay 102 thereby maintaining thatrelay energized and permitting the relay 103 to deenergize. Relay 103upon deenergizing opens an additional pointin the impulsin g circuit atsprings 123.

The operation of relay 106 closes at spring 130 a circuit traceable fromground through that spring, through spring 126 and its make contact,conductor 1e10, through wiper 111 of the fineer allotter FA, conductor81 to springs 37, through the winding of magnet 10 ot the finder F togrounded battery, with a parallel branch to the winding of relay 11,through resistance to grounded battery. Magnet 10 and relay 11 energizeover this circuit, the former to release the wiper to permit it to alignitself with the remail'iing wipers oi the switch, but since the finderis assumed to be standing upon the contacts of the calling line, thiswiper 32 is already aligned with the remaining wipers of the switch, andthe energization of relay 10 therefore performs no useful function. Thecomplete energization of relay 11 connects the calling line to the linerelay oi" the first selector E, that circuit extending from groundthrough the lower winding of the line relay of E, conductor 30",throughthe springs 39, wiper 32%, line conductor 1, thrtuigh the subscribersloop to line conductor 2, wiper 30, springs 38, conductor 3 through theupper winding of said line relay to grounded battery. lhe line relayenergizes and closes a circuit for the release relay of the selector,that relay energizing to send back ground over the conductor 31 in thewell known manner, that ground serving to maintain relay 11 in. itsenergized position. Relay 11 upon energizing ope-rates spring 36, toclose ground through the wiper 31, which is now engaging the privateconductor 6 associated with the calling line A, to guard the connectionagainst intrusion by a connector.

The calling subscriber is now connected to the first selector and theusual dial tone is audible to notify that the equipment is in readinessto receive the impulses from the calling device, to extend theconnection to the desired line. Returning now to the equipment R, thewiper 116 of the line equipment LE continues to revolve and fter abrief. interval loses the ground which is present upon the contact 7?,thereby opening the circuit of relay 106 which falls back after abriei": interval. Relay 106 upon falling back opens the circuit ofrelays 105 and 10 i, permitting those relays to deenergize, the formerto open at springs 127 the circuit of the magnet 101 of the finderallotter F A, that magnet deenergizing to advance the wipers lit) to 1l3 onto the next rontzirts in thew-w ll lino znzuiner. Th nation (it 1Wid 1ft.

itlj.

l eeenew i023, there- .ipinent R to normal in mess nu die net-t (111. 1

letter EA t'unetix her to pres group. us i.

innit-3r.

on minted equently huppen that the inder not It will most of the i r Fwill not be standin contacts of the calling line when a cult ited. andthut the control equipment wipers one or more to bring them intoengzgedes Assume here to L cont-nets. time line A is calling. the wipersof F standing in the position shown in Fig. l. in which use it will benecessary to more them two steps in order to bring them into engagementwith contacts and 1" in which the calling line termiengl'ee'e contacts"3" and 1. respectively, i'iper 11G enguges the contest i'. which renotthe tinder F. Since 1* is not standing upon the eontuet o. wiper 116will not romplete (he Circuit hr the winding of relay 106, d the pieireuit will be left intact preparatory to sending impulses to the mug 1ot the tinder F. \Vhen the wiper 11S Zh'l lkfi to engage the Contact F,a circuit tiny be trueed from ground through contact wijer 118.conductor H9. springs 12 5. "s 132. to eeiiduetor 1'12. wiper 113 oftinder all tter FA, conductor 83 and wiper 32 of the tinder l .nee overtwo paths in purillel, the one hreug'h springs 79 through the winding ofl ntor magnet '75 oi" the finder F to ttery energizing thut magnet if iil iinlieztted by the arrow. the wiper 32 renaming upon the net 122.being held there JV pawl whieh is controlled by the mag- U. Since twosteps we required to ring); the wipers ot 1* into engagement with tot-tsot' the walling line. and siure the wiper 116 r the line equipment LE:ow engaging the tentmt having moved to the Contact i wh n the wiper 118moved ott (rt contact \V, no circuit will be (ompleted tor the relay106. and an additional impulse will he sent to the nmgi'net '75 when thewiper 11S eneounters contact \V, the eireuit heing the same as before.\Vheu the znzi net T53 uguiu ful 4 buck and udrunees the wipers 3U :31and. 33 another step. wiper 3O engegt the eontu-t 2" and wiper 2-33enres (-oi'zturt 1 those rntricts being the bun-t ot the milling line.\Viper 32 still retxined by Bra-min ng lJIlWl 502. re-

in. h it contact in and at the end of the inn when wiper 11(3 ot theline equipnu. Ll'l moves lIltU engugrcinent with the Pon'uet g, u I maybe traced from irround through w 110 of the tinder uh letter FA,eondir-t r 8 wiper 32 now ening eontuet I). render-tor (z. contort y.wiper 116. eondn-vtor HT. springs 128, through the wint'iing et relay106 to grounded butter energizing that reluv whirl: muses the linder tohe switched through in the manner hereinbetore exple 'ihe rri:Slll)FCT'il)tl' then heirs 41,. mp1 i /v up 1 hit. it it... mu intihpuLi tr: llL ta ling derirs in uwroz'di .3 with the digits of the numberof the cur ..d station. the first digit operating the first selector Eto elevate the wipers 4U. 41 and if. \erti :dy upper e the desiredlevel. The r-releetor E then rotates :uitomutienlly under eo '(d of thetesting; eireuit through wiger 1, coming: to rest upon the eontzu-ts ofthe first idle trunk line. assumed to he the mutants ll 44 and 45 oi thetrunk line lending to the eoz'ineetor H.

ing station. Relay 1 eirruit and closes a eirem" ill. which niergizes toprepare the iinpui- Mg; irireuit nt springs 5:2. s pplies ground toholding; eonduetor at 52. and upuiies .e'i-oiuzil to the release leondurttir ll the .)';)(.';li((l relnys of the i tinder F in their oper-:iied position. When the iripulsing device :it the substation Ainterrupts the eirvuit 0t" reluy 13 in :iectu'dnnee with the next digitsit m UL

of the call number, line relay 13 falls back, and delivers impulsesfirst to the vertical magnet 15 over the circuit including relay 16 inseries, that magnet and relay operating to elevate the shaf" and wipers68 to 70, inclusive, vertically, the latter ren'iaiir ing energizedvthroughout the impulsing to perform certain control functions. The firstvertical step of the shaft operates the offnormal spring 55, in the wellknown manner, so that when the relay 16 falls back at the end of theimpulse series, a circuit is extended to the rotary magnet 22 and therotary multiple relay 19, to which the next digit dialled into the linerelay 13 is delivered. Atthe end of the second digit dialled into theconnector H, the wipers G8, (39, and 70 are positioned upon the contactsof the calling line, assumed to be the contacts 71, 72, and 73, whichare connected by the usual multiple cables 4t, 5 and 8 to the lines 3,4, and 5, of the substation B. In order to avoid unnecessarycomplications of the .drawing this multiple cable is omitted,

being indicated by correspondingly numbered wires. The operation of theconnecor H from this point on depends upon whether or not the called.line is busy at the moment. Asslnne first that it is busy. Contact 72,associated with the called line, will contain a ground potential if theline is busy. After the wipers have come to rest on the contact andbefore the slow acting multiple relay 19 falls back a circuit may betraced from ground on contact 72, through wiper 69, spring 90 and itsmake contact, springs through the winding of busy relay 18 to groundedbattery, energizing that relay which looks itself to release trunkconduct-or grounded at spring 50, through spring 59, the normally closedc011- tacts controlled by spring 90, those contacts being closed whenthe relay 19 restores an instant later, through spring and then throughthe winding of the relay to grounded battery. The calling subscriber isinformed of the busy condition of the line by the busy tone from thebusy generator placed on the line through springs 62, in the well knownmanner. The calling subscriber upon hearing this tone will replace thereceiver and release the connection in the manner which will beexplained hereinafter. Assume however that the calling line is idle atthe time the Wipers (38 to 70, inclusive, are positioned upon thecontacts associated with it. In this case the contact 72 will containneither battery nor ground potential, and the connector H will establishthe connection to the contacts 71 to 73, inclusive. During the operationof the rotary magnet 22, to rotate the shaft bearing wipers 68 to 70into connection with the contacts 71 to 73, cam 93 is opera-ted upon thefirst rotary step, closing springs 92 preparatory to switching theconnector through if the called line be idle. When the relay 19 fallsback after the wiper (39 is positioned on contacts 72 and found thatthat contact contains no ground potential, a circuit may be traced fromground through springs 51, OifdlOIlDitl springs 92, springs 60, spring94, winding of switching relay 20 to grounded battery, energizing thatrelay which looks itself from ground on spring 51, through springs 65and then through the winding of the relay to battery. Switching relay 20upon energizing places ground on contact 72 at springs 6-1 through thewiper 69, that ground marking the line busy to other connectors toprevent intrusion upon the pending call. Relay 20 at springs (33 and 67connects the wipers 68 and 7 O to the remainder of the connector,establishing a ringing connection to the called line. Interruptedringing current projected out over this connection from the generatorGen. under the control of the ringing interrupter RI, the circuit thatthe ringing current traverses being the usual and well known circuitwhich is conductive to alternating current and open circuited to thedirect current, because of the condenser at the substation B. lVhen thecalled station B responds to the call, by removing the receiver from thehook switch, a direct current bridge is closed across the conductor tothe line, energizing the ring cut-oif relay 17, which cuts off the ringand switches the connector through as usual. Ring cut-ofi relay 17 uponenergizing operates springs 56 and 58, extending the connection from thecalled line through to the back ridge relay 12, which furnishes batteryto the transmitter of the called station. Relay 12 energizes and atsprings 47 and 18 reverses the polarity of the calling line A in theusual manner, placing the two stations in a telephonic connection overwhich the conversation is carried on.

Release lVhen the station A and 13 have completed their conversation,and both replace their receivers, ground is removed from the releasetrunk conductor at springs 50 by the deenergization of relay 14, andfrom the connector holding conductor by the deenergization of backbridge relay 12 and release relay 14 at springs to and 51, respectively,whereupon all relays which were locked to the conductors are released,and restored to normal in the well known manner, placing the equipmentin its normal position in readiness for the next call. It will beunderstood of course, that the wipers of the finder F, remain upon thecontacts leading to the calling line A, until the finder F is seizedagain and operated into connection with some other line.

Line equipment rem/ting aver Busy line After the finder F has connected.with the calling line A, and at springs Z113 supplied ground to theprivate conductor 6,

and after the connector H is connected with the *alled line B, and atsprings 61 applied ground to the prirate conductor 5, those lines areprotected from intrusion either by a connector or by another tinder. Theline equipment LE continues to revolve, the wiper 117 testing theprivate conductors of the Various lines in order. \Vhen the wiper 117engages the contacts of the private conductor (3 of the calling line A,a circui "an be traced from ground upon that conductor, through wiper1.1T, conductor 1%, through normally elo'ed springs 121:, through theupper windn f 1 relay grounded battery, which at springs 121 ground andstart re circuit from the is 113) and 115, res nc irely. Since the r gline A is in use at is time a direct current bridge is closed across it,and iii the relay 102 were not provided to open the testinc" circuit,the relay would e1, each time the \x'ipers 110 and 118? on;

the con c s ass ciated with the line This would result in nnn vssaryoperation ot the hnder, am in a would protilt. 11110 31151111113115 ducean undes the callir' wipersof in Fig. "2', the private ages the coals.

mince the 1 the receiver from the substation A does not applv ground tothe private condn 1- a there rith.

.1 1 and since too 1 grounded until the tin-L h the calling connector hereceiver is r 1 d betoie die ma call the 1' moved from the switc tinderhas connected with t The line coi'iductors 1 a 1 associated pilrateconductor 1; are connectei to the banlts oi the connectors through theusual normal gized during the initiation of a call, a

ground was connected through re stance iii), springs lili, C()ll{l1l(t0l11 through the wiper 111 to the conductor 81, hence Li on the windirn otrcnay 11 and re- .icc to grounded battery. Relay 11 so constructed thatthe springs 3-1 close before the remainder of the springs are moved.that constriwion being old and well known to those i the art. When the"e r 11 s in serie with rei-1s sulticic'. strcn gth uowcrer i does notigth 1011! l v energize and ainder of its springs. When iclts up theground on con- .11 is short circuited troni that wiper, through and 115break \"UliLIH'l, springs 31, L.;l'(. 1l ':ll tne upper terminal or therelay, the liner terminal havin the wiper '21 I 1 din-(or n,

Y been grounded P bi. \Vhcn the i oni conductor 100 of the eipiipnientll energizes to tch through, the finder, rexij. 11, is prercd tron:cntrn'hcing bccai'se o? the shorteuit, but the equipment It and thefinder ailotter 1 A are operated in the usual manu 1, the former torestore to normal and latter to see out the next idle tinder of t egroup. \Yhen the line equipment Ll) re a es far enough s; that the wiper111 in engages the contact 6 ground potenial will be present on thatcontact, and the relay 10' will energize to guard that line fromintrusion by the control equipment R.

leturniug now to the deencrgization of magnet 101 01 the tinder allottcrFA to ad- \JHLQ the wipers lid-11 1 one step in s arch ot' the nextidle. Assume that the step positioned the wipers on the contacts towhich coinluctors 80S3 are connecterl and that the finder F is busy atthe moment. Conductor 81 will receive a ground potential from therelease trunl: conductor, as explained above, that ground being pickedup by wiper 11.1 to complete a circuit over which magnet 101 is againenergized, that circuit being trace able through wiper 111, conductor140, spring 126 and its break contact, conductor H3, springs 11 1,conductor 114, spring 127 and its break contact, conductor 115, throughthe winding of magnet 101 to grounded battery. Magnet 101 againenergizes and opens the above circuit at springs 114, falling back toadvance the wipers of FA one step. If the finder associated therewith isbusy, wiper 111 will pick up another ground, and the magnet 101 willoperate in the above buzzer like fashion until that wiper loses ground,at which time the wipers 110-113 will be brought to rest upon thecontacts of the idle finder.

From the foregoing description it is apparent that I have designed a newuseful finder system which is simple in its construction and which canbe easily maintained. In order to avoid unnecessary complications of thedrawings, I have shown the system in its simplest form, that is with thecalling line multipled only through one finder group and through oneline equipment group. In a commercial installation however, I propose tomultiple the line conductors to two or more finder groups and to two ormore line equipments, thereby increasing the reliability and speed ofthe system. With the line equipment such as shown in Figs. 3 and 4, I amable to rotate the wipers at the speed of about 25 revolutions persecond, since the wipers are double ending, the lines are tested at therate of 50 per second. By multipling each line conductors to two of theline equipments, and by spacing the wipers of the two line equipmentsdegrees apart, each line is tested every quar- .1 ter of a secondinstead of every half a second as is the case when a single lineequipment is used. Since the line equipments are being driven by acommon motor, it is not difficult to space the wipers in this manner andto maintain that spacing. Each line equipment and its associated controlequipment R, has access to a different group of finders, through thefinder allotter such as FA. In this manner the calls are doubly tested,so that in the event one line equipment fails to function properly dueto a mechanical or electrical defect, the other line equipment will pickup the call a quarter of a second later and handle it in the usualmanner. In the event of serious trouble in one of the line equipments,the wipers can be thrown out of gear, and repaired at leisure, withoutin any way interrupting the service of the line group, since the otherline equipment will handle all of the calls occurring therein at thattime. Moreover, I have shown the invention applied to a twenty-five linesystem, that being a convenient size and is shown by way of exampleonly, as it is entirely possible to appl the same principles to largerline units 0 50 or lines or more.

\Vhile I have chosen to show the invention in connection with theequipment of a particular design, I have done so merely by way ofexample as there are many modifications and adaptations which can bemade by one skilled in the art without departing from the scope of theinvention.

Having thus described my invention, what I consider new and desire tohave protected by Letters Patent is pointed out in the ap pended claims.

1. In a telephone system, a switch mechanism containing a shaft, aplurality of wipers mounted on said shaft, the entire contacting surfaceof said wipers being disposed in a plane containing the axis of saidshaft, a plurality of contact sets arranged in a semicircular bank andaccessible to the contact surface of said wipers, a plurality ofcontacts in each of said sets, one for each of said wipers, means forrotating said shaft to move said wipers from one contact set to another,said contacts being so shaped and arranged with respect to each otherthat the wipers engage their respective contacts of a set at differenttimes in a definite sequence and depart therefrom at different times inanother definite sequence.

2. In a telephone system, a switch mechanism containing a shaft, aplurality of wipers mounted on said shaft, the ends of said wipers beingdisposed in a plane containing the axis of said shaft, a plurality ofcontact sets arranged in a semicircular bank and accessible to saidwipers, each of said contact sets comprising a private contact, two linecontacts, a marking contact and a pulsing contact, said wiper assemblycontaining a wiper for each of said contacts, said contacts being sospaced that the private wiper engages its contact first, the two linewipers engage their respective contacts simultaneously and before saidprivate wiper has disengaged its contact, said marking wiper engages itscontact before said line wipers disengage their contacts, and saidpulsing wiper engages its contact after said private and line wipershave disengaged their respective contacts and before said marking wiperhas disengaged its contact.

3. In a telephone system, a switch mechanism containing a shaft, aplurality of wipers mounted on said shaft, a plurality of contact setsarranged in a semicircular bank and accessible to said wipers, aplurality of contacts in each of said sets, means for rotating saidshaft to move said wipers from one contact set to another, said contactsbeing so shaped and arranged with respect to each other that the wipersengage their respective contacts of a set in a definite sequence, andall wipers leave the contacts of one set before any wiper engages acontact of the next set.

4. In a telephone system, a switch mechanism containing a shaft, aplurality of contact sets arranged in a semicircular bank, each of saidcontact sets comprising a prillO vate contact, two line contacts, amarking contact and a pulsing contact, a set of wipers mounted on saidshaft comprising a wiper for each of the contacts in said contact sets,means for moving said shaft and wipers at a uniform speed said wipersengaging their respective contacts in the order named, and impulsingwiper engaging its contacts less than one half of the time during saidmovement.

The combination with a shaft carrying a plurality of wipers having knifeedge bearing surfaces aligned in a plane through the axis of said shaftand a means for rotating said shaft, of a bank contact arrangementwherein the wipers engage their respective contacts in a definitesequence, remain engaged with their respective contacts for differentperiods, and depart from their respective contacts in a differentdefinite sequence while said shaft is rotating at a uniform rate.

(3. In a telephone system, a switch mechanism containing a shaft, aplurality of double end wipers on said shaft disposed in. planes lyingat right angles to the axis of said shaft, a collecting ring for each ofsaid wipers having its contacting surface parallel with said shaft anddisposed concentrically to said shaft, and a brush for engaging thecontacting surface of each collecting ring, said brushes lying in planesparallel to the planes of said wipers and midway between adjacentwipers.

In witness whereof, I hereunto subscribe my name this 7th day ofOctober, A. D. 1927.

RUDOLPH F. QTEHLIK.

